Destination Alternate Requirements
Knowing when and how to select destination alternates is critical for flight safety, ensuring that pilots always have a viable backup if conditions deteriorate or unexpected events occur at the destination.
Destination alternate requirements specify when and how an alternate airport must be planned for IFR flights. These rules ensure that, if landing at the intended destination becomes impossible or inadvisable, a safe and suitable alternate is always available. The selection and number of alternates depend on factors like weather forecasts, available runways, and the nature of the destination aerodrome.
Quick Check
Under what conditions is a destination alternate NOT required for an IFR flight?
Go beyond the textbook.
Explanation
Definitions and Types of Alternates
- Destination Alternate: An aerodrome designated in the flight plan to divert to if landing at the intended destination is not possible or advisable.
- Take-off Alternate: Used if a return to the departure aerodrome is not feasible shortly after take-off.
- En-route Alternate: Suitable for emergency or abnormal situations during the cruise phase.
When a Destination Alternate Is Not Required
A destination alternate is generally mandatory for all IFR flights, but there are two main exceptions:
- If the destination has at least two separate usable runways (each with its own instrument approach based on different navigation aids), the flight time is less than 6 hours, and weather forecasts for one hour before to one hour after ETA predict a ceiling of at least 2,000 ft (or circling height plus 500 ft, whichever is higher) and visibility of at least 5 km.
- If the destination is an isolated aerodrome with no suitable alternate, provided the weather meets alternate minima and additional fuel is carried (trip fuel, contingency, plus 2 hours cruise fuel).
When Two Destination Alternates Are Required
Two alternates must be planned if:
- Weather forecasts/reports for the destination indicate conditions below planning minima between one hour before and one hour after ETA.
- No meteorological information is available for the destination.
Factors in Selecting a Destination Alternate
- Weather conditions and forecast at the alternate
- Runway suitability (length, surface, lighting)
- Availability of instrument approach procedures
- Aerodrome operational status and services
- Distance and fuel requirements
Alternate Airport Planning Considerations
- For PBN operations, at least one aerodrome (destination or alternate) must have a non-GNSS approach available.
- The departure aerodrome may serve as an alternate if it meets all requirements.
Take-off and En-route Alternates
- Take-off alternates must be within a specified flight time, depending on aircraft type and engine configuration.
- En-route alternates are chosen based on suitability in case of emergencies during cruise.
Understanding these requirements ensures compliance with regulations and enhances safety during flight planning.
Key Points
Exam Traps & Typical Mistakes
Example Exam Questions
When must two destination alternates be selected during flight planning?
Which of the following is a key factor when selecting a destination alternate aerodrome?
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